某油井P110油管在拉升过程中发生断裂。采用化学成分分析、力学性能检验、金相检验和腐蚀产物分析等方法对P110断裂油管失效原因进行了分析。结果表明, 地层水中的溶解氧造成油管表面发生腐蚀, 形成腐蚀坑。腐蚀导致油管厚度减薄, 承载能力下降, 最终形成裂纹发生断裂。

A P110 oil tubing of oil well fractured in stretching process. The fracture reasons of the P110 tubing were analyzed by means of chemical composition analysis, mechanical performance test, metallographic examination and corrosion product analysis. The results showed that the dissolved oxygen in formation water caused corrosion on tubing surface and pitting appeared in some locations. At the same time, tubing thickness reduced and capacity declined because of corrosion. So cracking appeared and the P110 tubular fractured.